Safety device



Nov. 17, 1959 J. RABlNow 2,912,933

SAFETY DEvxcE Filed Jan. 24, 1944 2 Sheets-Sheet l FIG. 2.

l2 V 3l 30 25 24 /l F I6. l.

5 2 27 23 22 9 a ./Acoa WIW/ow Nov. 17, 1959 J. RABlNow 2,912,933

SAFETY DEVICE Filed Jan. 24, 1944 2 Sheets-Sheet 2 FIG. -4. F I6. 5.

I mvENToR JACOB RAB/NOW SAFETY DEVICE Jacob Rabinow, Washington, D.C.,assgnor to the United States of America as represented by the Secretaryof the Navy Application January 24, 1944, Serial No. 519,456

6 Claims. (Cl. 102-70.2)

(Granted under Title 35, U.S. Code (1952), sec. 266) This inventionrelates to circuit making and breaking devices and more particularly toa novel inertia-arming switch for use in an electrical device, such as afuze, in a projectile.

An object of this invention is to provide an inertiaoperated powdertrain interrupter and switch for projectile fuzes, which, when actedupon by a sustained force of set-back, actuates one or more switches andalso establishes a connection between a squib and a booster charge.

A further object of this invention is to provide aninertia-operateddevice in which a rotor having a passage extending therethrough isrotated by a sustained force of setback, whereby it moves the passageinto position to establish a connection between an electrically redsquib and a booster charge, and also operates one or more electricalswitches. A toggle is provided which tends to retain the rotatableelement either in its normal or unarmed position, or in its armedposition. Retarding means, such as an escapement, is provided to retardro tation of the rotating element and thus assure that the device willbe actuated only by a sustained force of setback. The retarding meansalso delays the arming of the device until the projectile has traveled asafe distance,

and allows time for the heating of electronic tubes if such are employedin the fuze. The new device resets to a safe position if theacceleration is not maintained for a proper duration, and remainsunresponsive to a sudden shock or to the cumulative effect of repeatedshocks. ln this way, premature explosions resulting from the shock oftiring or from rough handling are avoided.

These and further objects will be apparent from the followingdescription and the accompanying drawings, in which Fig. 1 is a top viewof one embodiment of the invention for use in an electrical fuze,showing the parts in their unarmed or safe positions, with sectionsbroken away to show details of the structure;

Fig. 2 is a front elevation of the device shown in Fig. 1',

Fig. 3 is a rear elevation of the device shown in Fig. 1;

Figs. 4 and 5 are vertical sectional views taken on lines 4 4 and 5-5 ofFig. 1, respectively;

Fig. 6 is a vertical sectional view taken on line 6-6 of Fig. 1 butVwith the rotor in its armed position, and

Fig. 7 is a perspective view of the rotor of the device.

Referring to the drawings, the numeral 10 represents the chassis or baseplate of the device which has an opening 36 therein for a purpose whichwill be explained presently, and to which are attached supportingmembers 11 and 12 by means of bolts or other suitable means. Stub shafts13 and 14 carried by supporting member 12 carry notched or toothed wheel15 and rocker wheel 16, respectively, the latter having pins 17 whichcooperate with the notches in Wheel 15 to constitute an escapement.Supporting member 11 supports one end of a semicylinder 18 of insulatingmaterial, the other end of the semicylinder being keyed to, and servingas a support for rotor 19. Additional support for the rotor is providedby shaft 20 2,912,933 Patented Nov. 17, 1959 Cir which connects wheel 15and the rotor, and serves as a driving connection between the two. Thecentralportion of semicylinder 18 has a flat side` 21 which engagesresilient metal strips 22 and 23 mounted on the chassis 10. When thesemicylinder is rotated, its round portion bears against the resilientmetal strips 22 and 23 and ex erts a cam action against them, forcingthe metal strips into engagement with contacts 24 and 25, respectively,which are also carried by the chassis 10.

The rotor 19 carries a weight 26 mounted near its periphery so as tocause rotation of the rotor when a force of setback is applied. Therotor 19 also contains an opening 27 which diminishes in diameter nearthe centerY Y' of the rotor where it communicates with a passage 27aextending at an angle from the line of opening 27.

Passage 27a and opening 27 form a passage which eX tends entirelythrough the rotor transversely thereof. An electrically operable squib S(shown only in Figs. 3, 5 and 6) is adapted to be inserted in opening 27and is connected to contacts 32 and 33 which lie on the periphery of therotor near the outer end of passage 27a. The passage 27a serves as aconduit for the electrical connections 34 and 35 between the squib andthe contacts 32 and 33.

A crank-shaped connecting member 28 is secured to the notched wheel 15and rotor 19 and extends upwardly in front of the shaft 20 between thewheel and the rotor. This member 28 serves to increase the angle oftoggle action at the end of the arming cycle so that 270 degrees oftotal rotation of rotor 19 may be obtained. A spring 29 attached at oneend to post 29a on the chassis passes upwardly behind shaft 20 and isattached at its other end to the central portion of connecting member28.

Resilient metal strips 30 and 31 attached to the chassis 10 bear againstthe periphery of rotor 19 and make electrical contact with the contactpoints 32 and 33 whenv the rotor is in its armed position (Fig. 6). Thiscloses what is called the squib circuit.

The operation of the device will now be explained. With the parts of thedevice in their unarmed positions as shown in Fig. l through 5, switches22-24 and 23-25 and the switch which comprises resilient elements 30 and31 and contacts 32 and 33 are open. Passage 27-27a in the rotor 19 is inthe position shown in Fig. 5, and in this position the squib and thebooster charge (not shown) are separated by the rotor so that if thesquib is prematurely tired, the flash cannot reach the booster chargethrough opening 36 to ignite the booster. Due to the fact that one ofthe pins 17 lies in an end notch of the notched escapement wheel 15, thelatter and rotor19 are at the limit of their clockwise movement, asviewed in Fig. 4. The toggle consisting of spring 29 and connectingmember 28 tends to maintain the rotor and notched wheel in this initialposition, in which the device is unarmed.

When the device is acted upon by a force of setback caused byacceleration in the direction of the arrows in Figs. 2 and 3 of aprojectile containing the device, the inertia of weight 26 causes it toshift to the right, as viewed in Fig. 5, thus rotating the rotor 19 inthe direction of the dotted arrow in Fig. 5. As soon as the weight 26has moved the toggle through its dead center position, the toggle willcontinue the rotation of the rotor until it reaches the position wherethe center of gravity of the rotor is nearest to the base, in whichposition the rotor is retained as long as the mechanism is underacceleration of sufficient magnitude to overcome the force of spring 29.After the cessation of acceleration, the spring 29 will continue torotate the rotor 19 until stopped by the limiting action of theunnotched portion of the escapement wheel 15. In this position the squibpassage 27 is directly in line with the opening 36 and will detonate thebooster when the squib is tired.

lnotches on the periphery of wheel 15. the rotation of rotor19'bythe;escapernent:prevents the device from being armed=prematurelybythe Vshock of firing or from rough handling. n Also, theretardingaction of thelescapementtdelays the arming of :the device until apredetermined period vof time has elapsed during which the projectiletravels a certain safe distance away from the projector from which itAwas red, and during which period anyelectronictubes which may be incircuit with the device are allowed to heat.' If therotor is vturned ashort distance Lby an unsustained acceleration caused, for

example,A bydropping the device, thespring 29 willreturn the rotorandthe notched wheel 15 to1their original positions'. after tenninationofthe shock, so that the device remains unarmed andrepeatedshocks have ncumulative effect. y

`Rotation of the rotor to the position shown in Fig. 6 rotatessemicylinder 18. Rotation of the semicylinder causes its round portionto bear against resilient metal strips 22 and 23, thus forcing them intocontactwith the contact members 24 and 25 and closing the circuitsincluding those contacts, for, example, .A and B battery circuits.Ifvitis desired to close the contacts 22--24 and.2325 earlier in thearming cycle, springs 2,2 Aand 23 may be weighted with sufficient massso that Vthe-applicationof setback-causes the springstobend and thusclose thesecontacts. The actionof the .semicylinder-will then be merelythat of a lock to keep these contactsclosed after the acceleration hasceased. When the rotor reaches the nal or armed position shown in Fig.6, the contactors consisting of resilient metal strips 30 and 31`engagecontact points 32 and 33 mountedon rotor 19 so The retarding of thatupon operation of the fuze, the squib S will be fired electricallythrough contactors 30 and 31, contacts 32 and, and conductors Stand 35.`When rotor19 is in the -position shown in` Fig..6, thepassager34providesa direct connection between the squib S and Va .booster charge(not shown) so that when thesquib is red,'it will flash into the boostercharge through opening 36 and ignitefthe booster. The initial andtnalpositions of the rotor are determined by varying the number and positionofthe notches on the periphery of notched wheel.15thus limiting therotation ofnotched wheel-15, and ,consequently the rotation of the rotor19. Other means such as detents, may be used to determine thesepositions of the rotating elements, if desired.

Instead of mounting the squib in Athe passage 27 as described above, thesquib may be mounted adjacentthe rotor in such a positionthat the rotorprovides a-safety gate between the squib and the boosterwhen therotor-is in itsunarmed position, andprovides a connecting passagebetween the squib and the booster through passage 27.-,2711 when therotor-is in its armedposition` shown in Fig-6. In such an embodiment ofthe invention, the contacts 32 and 33 would be connected togetherelectrically-so that rotation of the rotorl to, its armed positionshown'in Eig.'6 wouldkprovide awconnection between resilient :stripstland l31 to arm the squib.

As explained above, therprovision of kthetoggle and the escapement inthe device assures thatv the device will beactuated only-by a sustainedforce of setback, thus avoiding premature` explosions resulting from theshock of ring ori-from rough' handling. The delay interposed by theescapement vassures thatzthe'device will be boresafe-andallows time forthe heating ofy electronic tubes, if-such are employed in the-fuzecircuit. Once the toggle passes deadcenter, it assures that the rotor-will reach the desired armedposition, -due to the fact that the springin the toggle will cause the-rotor to continue its rotation even thoughthe force of acceleration which initially actuated the deviceV hasceased. In constructing thedevice, the chassis 10and the rotor "19 maybe of `nonconducting material if desired, or ii such material is notused, suitable insulation will, of course, be required betweenelectrically conducting elements and the chassis 10 and-rotor 19.

The invention herein described may be manufactured and used by or forthe Government of the United States of America for governmental-purposeswithout the payment of any royalties ,thereon-onthercfor.

I claim:

rl. In an inertia-operated device `for projectile fuzes, af

rotor'havi'ng a weight mounted therein near-the periphery of saidrotor,.the rotor having an explosion discharge passage adapted rtoycontain anpelectrically detonatable `s ,quib and being movable byasetback force on the weight from an unarmed position inwhichvthe-passage is inoperative toward an armed. position in which thepassage, is operative to discharge, a earn rotatable with said rotor, aswitch for closing a circuit being operable by said cam, a switch armengageable with the `rotor ,for closing a squib circuitto conductcurrent to detonate the Isquib whenthe yrotor lis in its,;arrnedposition, a toggle connected to and tending to maintain said rotor inArespectively-itsunarmed and armed positions, means for retarding saidrotor whilerotatingto vthe latterposition, and means ontherotor coacting,with ,a part of the retarding means for determining the respectivearmed/.arid unarmed positions of saidrotorpandtthe circuitfopen andCircuit-Closed positions of said cam.

2. in .a-.Setback switch, a potentially movable squib, a contactorxed atthe arming position of the switch .and comprisingthe terminal of anelectrical circuit for `detonating the squib, and an inertia-operablesafety device supportingthe s quibat an initially unarmed Vposition andcausing its eventualrnovementtoward the armed position, said devicehaving a conductor leading vfrom the squib and terminating in a contactdistanced lfronnthe contacter in said; unarmed position.

3 A ,projectile fune Yswitch comprising inertia-oper;-

- able element carrying an:electricallyiiiredsquib, a-spring toggledevice connected eccentrically to -said element, applying a p ull, ontheelement-toturn it ,-towardunarmed and armedpositions when exercisedatopposite .sidesof the turningaxis, a toothed escapement wheel coupledto the elementa rocker pin device actingon the teeth ltosloyv theelement when turned by components of ,setback and togglespring actionduring acceleration o -f ,tlreSWiiCk an untoothed portion on said wheelcoacting with .theroclr'er pin device to limit turning of the elementtoward itsrespective positions, and contact-making means renderedoperative by lsaid element for closing ari electrical circuit throughthe squib in the-arming position o-ffsaidelement.

4. A projectile fuze switch comprising an inertia-open,

able element carryingv an` electrically tired squib, a toothedescapement :wheel axially coupled `to .said element .and

spaced therefrom, ra spring toggle device located in `the space beingcoupled eccentrically toA-the element and wheel to applya pull to turnthem toward unarmed andarmed positions when exercised at oppositesidesofthe axis, ay

' escapernen-t-wheel, an off-centered shaft connecting said element andwheell in 'spaced relationship and serving as -a driving connectiontherebetween, a toggle device located in the space, consisting of acrank shaped member secured to j theelement and wheel and having aportion in proximity to the shaft, and an :anchored spring connected tosaid portiom- `Said toggle device applying a pull onthe element `closingan electrical circuit through the squib in the armi ing position of saidelement.

6. A projectile fuze switch comprising an inertiaoper able elementcarrying an electrically tired squib, a spring toggle device connectedeccentrically to said element, applying a pull on the element to turn ittoward unarmed and armed positions when exercised at opposite sides ofthe turning axis, a time-delay mechanism coupled to the element to slowthe element when turned by components of setback and toggle springaction during acceleration of the switch, means on said element to limitturning of the element toward its respective positions, and contact-making means rendered operative by said element for c1osing an electricalcircuit through the squib in the arming position of said element.

References Cited in the file of this patent UNITED STATES PATENTS1,311,104 Watson July 22, 1919 1,726,325 Varaud Aug. 27, 1929 2,403,063Elmer July 2, 1946 FOREIGN PATENTS 314,716 Germany Oct. 13, 1919 328,410Germany Nov. 5, 1920

